The objective of this proposed study is to determine the extent to which occupational exposures to parents account for tumors in offspring. We propose to study the relationship between parental occupational exposure and common childhood cancers by the case/control approach. Children less than 15 years of age will be studied. Cases of childhood cancers will be identified by the University of Sourthern California Los Angeles County Cancer Surveillance Program (CSP), a comprehensive population based tumor registry covering more than 7 million people. In children under 15 there are approximately 225 new cases of cancer in Los Angeles County each year about equally divided by the sexes. Over a five year period, the CSP should yield approximately the following number of childhood cancers: 325 leukemias, 200 brain tumors, 55 kidney tumors, 60 bone tumors and 75 connective tissue tumors. These cases will be the subject of our study. Neighborhood controls will be selected by an establised algorithm. Parents of cases and controls will be interviewed by a standardized questionnaire to ascertain complete occupational histories for both parents. Information concerning other exposures of etiologic significance and potential confounding variables will also be collected (age, race, socio-economic status, tobacco use, drug use, exposure to ionizing radiation, family history of malignancy and congenital malformation, non-occupational exposures, etc.). The collected information on occupation will be reduced to specific chemical exposures wherever possible and relative risks will be determined for the various occupations and exposures. In addition, we will examine the importance of timing of exposure (prior to, during, or after pregnancy), breast feeding, and the relative effects of exposure to mother or father. Identification of occupations or exposures that result in increased risk has important public health implications.